java - put listView child in a hashmap -

i'm trying fetch values listview loop , put them in hashmap. logcat keeps throwing error. can't figure out why. please! list view has @android:id/list , have extended listactivity on activity here code fetch values

liststudent=getlistview(); studentmarkslist=new arraylist<hashmap<string,string>>(); string student,obtained_value,max_value; (int i=0;i<liststudent.getcount();i++) {     view view=liststudent.getchildat(i);     studentidtxt=(textview) view.findviewbyid(r.id.student_id_ls);     obtainedtxt=(edittext) view.findviewbyid(r.id.obtained);     maxtxt=(textview) view.findviewbyid(r.id.max);     student=studentidtxt.gettext().tostring();     obtained_value=obtainedtxt.gettext().tostring();     max_value=maxtxt.gettext().tostring();     //updating new mark list array     hashmap<string,string>studentmark=new hashmap<string,string>();     studentmark.put(tag_student_id,student);     studentmark.put(tag_marks_obtained,obtained_value);     studentmark.put(tag_marks_max,max_value);     studentmarkslist.add(studentmark); } 

and here xml layout list

<listview     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:id="@android:id/list"     android:layout_alignparenttop="true"     android:layout_alignparentleft="true"     android:layout_alignparentstart="true"     android:layout_margintop="106dp" /> 

and here xml list items

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent">   <textview     android:id="@+id/student_name_ls"     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:paddingbottom="2dip"     android:paddingtop="6dip"     android:textcolor="#1e5401"     android:textsize="16sp"     android:textstyle="bold" />  <!-- marks label -->  <edittext     android:id="@+id/obtained"     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:paddingbottom="2dip"     android:textcolor="#acacac"     android:inputtype="numberdecimal"     android:numeric="decimal" />  <textview     android:id="@+id/max"     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:paddingbottom="2dip"     android:textcolor="#0b0b0b"     android:enabled="false"     android:editable="false" />  <textview     android:id="@+id/student_id_ls"     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:paddingbottom="2dip"     android:textcolor="#060606"     android:visibility="gone" />    </linearlayout> 

and problem on line "studentidtxt=(textview) view.findviewbyid(r.id.student_id_ls);" throws nullpointerexception please

you should use

liststudent.getchildcount() 

this because number of views in list view equal number of views see. not equal number of items in listview. if use getcount() indexoutofboundsexception because there no more views.